The present invention relates to a pneumatic tire, more particularly to an external structure of the sidewall portion capable of reducing the rolling resistance of the tire.
In recent years, in view of resource saving and global environmental problems, pneumatic tires are strongly required to decrease the rolling resistance.
The rolling resistance can be decreased by decreasing the energy loss in various rubber components of a tire.
However, if a tread rubber having a low heat generation property is used in order to decrease the energy loss during running, the road grip, braking performance and steering stability are liable to deteriorate, therefore, the use of such rubber has its own limits.
On the other hand, the sidewall portions of a pneumatic tire are largely deflected during running. With this deflecting motion of the sidewall portions, the tire shoulder portions or tread shoulder portions are subjected to large stress or deformation, causing an energy loss in the tread rubber or so called wing rubber disposed in the tire shoulder portion.